Good morning everyone we begin with -- breaking news from Australia what's likely the first significant breakthrough in the search -- Malaysia airlines flight 37. After a monthlong search and many false police task force officials now say that they have the most promising lead yet. In just the last 24 hours an American naval -- -- cater has detected two separate audio signals in a remote patch of the Indian Ocean. On this occasion two distinct -- -- returns what portable. Significantly. This would be consistent with transmissions. From both the flight -- recorder. And the cockpit voice recorder. But nailing down the signal locations will not be easy this part of the search area is nearly three miles deep. And batteries on the black box recorders is generally only last about thirty days -- south. And tomorrow marks exactly one month of course the only real confirmation will come when actual wreckage from that plane is found we've learned. Anything it's to be cautiously optimistic that's very interest and that's that piece of equipment that it's almost at the scene the first thing you saw that yellow torpedo. And that is called a -- within 27 and what that all do. -- searched the area under water with still photos and sonar middle sending images back to the ship and what they're all going to be looking for is not necessarily the black box right away they -- -- see debris field they once -- write my goodness we found a haystack. Then they go looking for the black box. Right and and going back to what you were saying we have to be cautiously optimistic here. According to experts it could take days before anything is -- around. And the deal is they haven't found the aircraft yet. So what they have found is something that is promising possibly believed possibly something that will lead them to the aircraft. But so far right now that's all they have they have a -- -- -- that's going off. They don't have actual. And -- great about this is the actual head in the investigation in Australia is saying how promising misses this isn't a bunch of London sin and so called experts sitting on a desk and saying this is encouraging. -- the guys heading up the whole thing right so. -- chipset heard this actually heard that paying the finger low Peter was that was able to hold that. What it would it sound as -- to hold that. For tuning in for frequency for two hours and twenty minutes the first time in for thirteen minutes the second time so that definitely means something we are hoping. The turning around trying to locate the signal get it takes three hours to turn around that massive shipment is dragging the signal -- -- -- that's happening. That other little torpedo like devices on its way to hopefully do the mapping so. Again it could be days right. -- -- -- And experts do say that there is water waves there's topography down -- that could send a pain to -- locate her. But the person heading -- -- it's not likely that it's anything other than possibly a black -- Let's hope so and of course as new major leads come in be -- to stay with ABC news for the very latest on the search for flight 370. Our next updates on America this morning as well as Good Morning America.

This transcript has been automatically generated and may not be 100% accurate.

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